Concrete is placed as a liquid and develops its strength as it cures over days or weeks. Curing is the process where the proper conditions for cement particles to hydrate are created and maintained, through which concrete gains its strength. The ability to place concrete as a liquid has many advantages including easier shipment, pumping concrete in ways similar to water, and the ability to place concrete into nearly any form on the project site. Concrete contractors in Portland, such as The Conco Companies, provide expert concrete services for complex projects throughout the Western U.S. Part of all concrete placement services is to test the strength of concrete as it cures to determine if it meets its designed performance specifications.
Concrete Testing Standards
Concrete strength testing is a well characterized and defined process. The American Concrete Institute (ACI) developed standards to ensure that concrete strength is consistent in every commercial project. ACI 318-14 defines that concrete compressive strength will be based on 28-day test results, with the average of three tests being the final value as long as no strength is below 500 psi or 10% below the specified strength. This means that while three day or seven day tests may be done to determine if the concrete is strengthening as designed, under most conditions, the 28-day test is the final determination of the concrete’s long term strength.
Concrete Testing Methods
Testing concrete in place, and not in the lab, offers the ability to determine when concrete formwork can be removed on new concrete and to determine the strength of existing concrete, for example, when a building use is changing and the structure strength needs to be re-evaluated accordingly. Testing methods can be destructive or non-destructive. While non-destructive methods are preferred, they do not measure the compressive strength directly, and if there is any question of the concrete’s strength, destructive measures will be used. Methods for in-place testing include rebound number, penetration resistance, pullout test, breakoff number, ultrasonic pulse velocity, maturity method, and cast in-place cylinders. Cast in-place cylinders are test cylinders that are poured when placing concrete and are tested after different periods of time to determine the progress of the compressive strength over time.
Conco’s mission is to be the best supplier of concrete services in the Western United States and to bring expertise, experience, and quality of each project. We continue to upgrade and expand facilities to better serve the growing market for commercial, educational, public works, and parking structure projects as well as other construction development. Please call or email for more information on how Conco can assist your next project with Confoam™, our cost-saving cellular concrete.
As one of the leading commercial concrete contractors in the nation, The Conco Companies provide the Western United States with a wide range of concrete services including producing and placing cellular concrete. Also known as foam concrete, cellular concrete provides customers with one of the most productive, cost-effective solutions in a variety of applications.
Our proprietary cellular concrete product is Confoam™, and is a lightweight, low-density fill material that we customize for each specific job. In addition we have the specialized production equipment and experienced crews that know how to expertly place the highly flowable material for optimal results. While lightweight concrete is typically a concrete made with aggregates lighter than typical stone aggregates and has a density + 120 lb. / cu.ft., cellular concrete uses the internal air cell structure instead of an aggregate and exhibits densities from 20 to 90 lb. / cu. ft.
Our cement-based slurry contains a high percentage of foam entrained into the plastic mortar and offers a perfect solution for filling challenging voids underneath slabs and tight, unstable trenches. Also Confoam has a fairly low carbon footprint that makes it “greener” than traditional concretes. Another advantage of using Conco’s foam concrete is that it is self-compacting, and thus eliminates the need for mechanical compaction, which means there is no impact on retaining structures or deep foundations.
Furthermore, cellular concrete can be produced to be lighter in weight than the site’s compacted base materials or native soils, and as such, provides an inexpensive solution for foundations. This also means there is virtually no settlement as Confoam can be produced to make the combined weight of the new structure less than or equal to the weight of the removed soil. And perhaps most importantly, placing cellular concrete is safer than traditional fill methods as it does not require employees to be placed in the excavation area.
Cellular concrete is just one solution The Conco Companies offer customers to help save time and money. Please visit our website or contact us to learn more about how we can help to get your next project off to a great start.
At The Conco Companies, we are one of the leading concrete contractors in the Western U.S. and offer a wide range of quality services and products. Our experience includes providing services for commercial, educational, parking and other construction development as well as public works projects. We serve California, Washington State, Oregon, Colorado and Nevada.
Along with our broad range of commercial concrete services including pumping, shotcrete, rebar fabrication and installation, trucking, and design/build, The Conco Companies also offer superior formwork. This all-important temporary structure is designed to contain and mold poured concrete until it hardens into the required shape.
As formwork controls the concrete’s position and alignment, it needs to be strong enough to support its own weight, that of the concrete, as well as the workers and any equipment or materials that will be used in the process. Over the last couple of decades, there have been major advancements in formwork that have resulted in greater cost-efficiencies and have improved workers’ safety.
The process behind creating topnotch formwork is a collaborative effort between the concrete contractors, engineers, and architects. The group must take into account factors such as the quality, cost, and safety requirements needed in order to design and implement forms that meet their project’s specifications. The materials used to construct the forms will depend on the type of job it is designed to do.
Forms used to be built out of lumber, but today, a variety of materials is used including plywood, aluminum, and steel as well as custom-made plastic and fiberglass forms. With the development of newer types of forms, it has helped to improve the safety, speed, and manageability on a jobsite.
Once the form is built, concrete is placed into it. After the concrete has hardened, the forms are disassembled or “stripped” and can be used again. It is important to not strip the forms or remove the shoring before the concrete has sufficiently cured and is able to support its own weight.
In the U.S many forms are now made from prefabricated modules that allow the forms to be assembled quickly and cost-effectively on the jobsite. The modules can be reused thousands of times whereas older wood forms had to be replaced much sooner.
The Conco Companies are a leading supplier of concrete services for the Western U.S. We got our start in the Bay Area in 1959 by offering clients the best value on a wide range of concrete services and products. Since that time, we have taken a leading role as one of the top concrete contractors in the region. We have four regional offices serving California, Nevada, Washington, Oregon and Colorado.